The public option currently does nothing, though the value is stored in the server. The goal is to make it so a list can be shared with your realm, if I recall correctly. I'm not certain how Tom, the original developer, planned to implement them that way, as I'd approach it a bit differently.

As for "and subs" this is only pertaining to characters, and it means that you also want any of their vassals (or subordinates) to also be included.